I typically keep mine reasonably small and discrete - typically doing as little as possible, but I've encountered some monster sprocs in my time which seem to be all out of keeping with the actual db model and the size of the project.
Tonight a friend told me that a team at his place had built a 250-odd line sproc for a project that I thought would be much smaller.
So - how big are your sprocs? Do you worry about putting too much logic in your database? Why do you make them the size they are (because it is a complex project isn't a good answer)?